As semiconductor technologies evolve, three-dimensional integrated circuits emerge as an effective alternative to further reduce the physical size of a semiconductor chip. In a three-dimensional integrated circuit, active circuits are fabricated on different wafers and each wafer die is stacked on top of another wafer die using pick-and-place techniques. Much higher density can be achieved by employing vertical stacking of integrated circuits. Furthermore, three-dimensional integrated circuits can achieve smaller form factors, cost-effectiveness, increased performance and lower power consumption.
In the process of manufacturing three-dimensional integrated circuits, known good die (KGD) and known good stack (KGS) tests are often performed through various testing probe card at various stages during the manufacturing process. Probe cards are one type of test structure used to perform electrical tests of dies. The probe card may be coupled between an automatic testing equipment board and a semiconductor die under test. The probe card makes contact with the semiconductor die through a plurality of probe contacts and the automatic testing equipment send signals through the probes to the die and reads the output and determines the performance of the die.